Group settings should honor user-set individual options

In the last commit, we added the ability to explicitly disable
boolean settings form the command line.

This commit changes group settings (like -optimize), to leave
them alone if set explicitly.

Examples:

   `scalac -Xlint -Ywarn-unused:false -optimize -Yinline:false`

The mechanism for such settings has also been refactored to
`MutableSettings`, to let use reuse this for `-Xlint`.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
index a8421c8b15..3590254128 100644
--- a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
@@ -679,4 +679,14 @@ class MutableSettings(val errorFn: String => Unit)
       else name + "[:phases]"
     )
   }
+
+  /** Internal use - syntax enhancements. */
+  protected class EnableSettings[T <: BooleanSetting](val s: T) {
+    def enablingIfNotSetByUser(toEnable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toEnable foreach (sett => if (!sett.isSetByUser) sett.value = s.value))
+    def enabling(toEnable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toEnable foreach (_.value = s.value))
+    def disabling(toDisable: List[BooleanSetting]): s.type = s withPostSetHook (_ => toDisable foreach (_.value = !s.value))
+    def andThen(f: s.T => Unit): s.type = s withPostSetHook (setting => f(setting.value))
+  }
+  import scala.language.implicitConversions
+  protected implicit def installEnableSettings[T <: BooleanSetting](s: T): EnableSettings[T] = new EnableSettings(s)
 }